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621.
Abdul-Wahab El-Rjoob Ziyad A. Taha Jamil Al-Mustafa Abdulaziz M. Ajlouni 《Journal of solution chemistry》2012,41(7):1079-1087
The formation constants K ML of Clarithromycin (CLA) and Roxithromycin (ROX) with Fe(III) and Fe(II) ions in methanol have been determined at various temperatures using a conductometric technique. The interaction yields complexes with metal-to-ligand compositions of 1:1. The conductivity data were analyzed using a computer program based on 1:1 stoichiometry from which the stability constants and the limiting molar conductance were obtained. The stability of these complexes was found to increase with temperature. Compared with Fe(II), Fe(III) forms more stable complexes with ROX and CLA. The values of the thermodynamic parameters enthalpies (??H °), entropies (??S °), and the derived Gibbs energies (??G °) were deduced from the dependence of the formation constants on temperature. The positive values of ??H ° and ??S ° indicate that the complexation processes is enthalpically unfavorable but entropically favored. The negative values of ??G ° show the ability of the studied ligand to form stable complexes and that the complexation process is favorable. 相似文献
622.
A screen-printed carbon electrode modified with both HRP and LOD (SPCE–HRP/LOD) has been developed for the determination of l-lactate concentration in real samples. The resulting SPCE–HRP/LOD was prepared in a one-step procedure, and was then optimised as an amperometric biosensor operating at [0, −100] mV versus Ag/AgCl for l-lactate determination in flow injection mode. A significant improvement in the reproducibility (coefficient variation of about 10%) of the preparation of the biosensors was obtained when graphite powder was modified with LOD in the presence of HRP previously oxidised by periodate ion (IO4−). Optimisation studies were performed by examining the effects of LOD loading, periodation step and rate of the binder on analytical performances of SPCE–HRP/LOD. The sensitivity of the optimised SPCE–HRP/LOD to l-lactate was 0.84 nA L μmol−1 in a detection range between 10 and 180 μMol. The possibility of using the developed biosensor to determine l-lactate concentrations in various dairy products was also evaluated. 相似文献
623.
Two sensitive and selective spectrofluorimetric and spectrophotometric stability-indicating methods have been developed for the determination of some non-steroidal anti-inflammatory oxicam derivatives namely lornoxicam (Lx), tenoxicam (Tx) and meloxicam (Mx) after their complete alkaline hydrolysis. The methods are based on derivatization of alkaline hydrolytic products with 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-Cl). The products showed an absorption maximum at 460 nm for the three studied drugs and fluorescence emission peak at 535 nm in methanol. The color was stable for at least 48 h. The optimum conditions of the reaction were investigated and it was found that the reaction proceeds quantitatively at pH 8, after heating in a boiling water bath for 30 min. The methods were found to be linear in the ranges of 1-10 microg ml(-1) for Lx and Tx and 0.5-4.0 microg ml(-1) for Mx for spectrophotometric method, while 0.05-1.0 microg ml(-1) for Lx and Tx and 0.025-0.4 microg ml(-1) for Mx for the spectrofluorimetric method. The validity of the methods was assessed according to USP guidelines. Statistical analysis of the results revealed high accuracy and good precision. The suggested procedures could be used for the determination of the above mentioned drugs in pure and dosage forms as well as in the presence of their degradation products. 相似文献
624.
Soliman AA Taha A Linert W 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,64(4):1058-1064
Adducts of Ni(II)-square planar complexes [Ni(beta-dik)(Me(4)en)](+), with a series of bidentate ligands (L), where beta-dik=acetylacetonate (acac) and benzoylacetonate (bzac), Me(4)en=N,N,N',N'-tetramethylethylenediamine and L=Me(4)en, 2,2'-bipyridine (bipy), ethylenediamine (en) and oxalate (C(2)O(4)(2-)) have been synthesized and characterized by spectral, thermal and magnetic measurements. Formation constants of the adducts formed from a series of ternary mixed Ni(II) complexes with the general formula [Ni(beta-dik)(diam)](+) with 1,10-phenanthroline (phen), 2,2'-bipyridine (bipy) and pyridine were spectrophotometrically determined. Thermodynamic parameters of the adduct formation between nickel(II) square-planar chelates and pyridine (py), 2,2'-bipyridine (bipy) and acetylacetone (acac) were also spectrophotometrically determined in 1,2-dichloroethane. The thermal stability of the isolated adducts was studied using thermogravimetry and the decomposition schemes of the adducts were given. 相似文献
625.
Hisham K. Fouad 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(2):193-197
The tetravalent and hexavalent uranium content of three Egyptian phosphate type ore samples namely; Sebayia, Abu Tartur and
Qatrani have been studied through selective leaching by hydrochloric acid at normal, oxidized and reduced conditions at an
amount of hydrochloric acid less than the stoichiometric value i.e. before phosphoric acid production. Oxidizing condition
is attained by incorporating 2% of manganese dioxide in the leaching cycle, whereas reducing condition is attained by adding
2% iron powder. The achieved results show that the amount of tetravalent uranium varies between 5 and 95%. As soon as the
achieved stoichiometric value of hydrochloric acid is sufficient to produce phosphoric acid both tetravalent and hexavalent
uranium dissolve by virtue of phosphoric acid complexing power for uranium. The chemical form of uranium in the ore determines
the type of solvent needed to recover it. 相似文献
626.
Hisham K. Fouad Abram F. Bishay 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(3):765-772
Uranium uptake from acidic solutions is comprised practically in this study into three main steps namely; adsorbent synthesis,
uranium uptake procedure, and desorption step. In this respect, two uranium adsorbents were synthesized from mineral processing
of ilmenite and talc. Titanium phosphate adsorbent (TP) was deposited from titanium sulfate solution obtained from ilmenite
sands processing. On the other hand, magnesium silicate adsorbent (MS) is prepared by sodium metasilicate neutralization of
the acidic magnesium bearing waste solution resulted from talc whitening process. Structurally and chemically the two adsorbents
were investigated by XRD, IR and SEM-EDX analyses. The studied factors affecting the uranium uptake onto TP and MS adsorbents
were uranium concentration (10–1000 ppm), acidic pH range (1–6), contact time, shaking time and solid to liquid ratio. The
uranium analysis was determined spectrophotometrically using arsenazo(III) dye where SEM-EDX analysis confirmed the uranium
uptake by adsorbents. The optimum conditions obtained were applied to uranium bearing, highly mineralized granite samples
(5200 ppm U) and black shale (40 ppm U). The uranium uptake was more than 98% for the mineralized granite samples and more
than 97% for shale. The loaded uranium was recycled by using 0.5 and 1M HNO3 in case of TP and MS with percentage recovery of 96 and 98% respectively. 相似文献
627.
Abdulaziz M. Ajlouni Ziyad A. Taha Khader A. Al-Hassan Abdullah M. Abu Anzeh 《Journal of luminescence》2012,132(6):1357-1363
A novel Aryl amide ligand H2L and its eight complexes, [LnH2L(NO3)2·H2O]NO3 [Ln=Sm(III), Er(III), Tb(III), Dy(III), La(III), Gd(III), Nd(III), and Pr(III)], are presented. The ligand and complexes were synthesized and characterized based on elemental analyses, molar conductance, IR, 1H and 13C-NMR, UV–VIS., and TGA studies. The conductivity data show a 1:1 electrolytic nature with a general formula [LnH2L(NO3)2·2H2O]NO3 The IR spectra reveal coordination of the ligand through the azomethine nitrogen and the phenolic hydroxyl of the ligand to the lanthanide ion. The coordinated nitrate ions behave in a bidentate fashion. The thermal decomposition studies indicate the presence of two water molecules in the inner coordination sphere. Under the excitation at 319 nm, the luminescence emission properties for Sm, Tb, and Dy complexes are observed. These observations show that the ligand favors energy transfers to the emitting energy level of these lanthanide ions. Furthermore, the antioxidant activity of the ligand and its Ln(III) complexes was determined by DPPH radical scavenging method, which indicates that the Ln(III) complexes exhibit more effective antioxidant activity than the ligand alone. 相似文献
628.
Ilhame Bourais Salma Elmarrkechy Douae Taha Bouabid Badaoui Yassine Mourabit Najoua Salhi Mohammed Merae Alshahrani Ahmed Abdullah Al Awadh Abdelhakim Bouyahya Khang Wen Goh Ching Siang Tan Souad El Hajjaji Nadia Dakka Naima Iba 《Molecules (Basel, Switzerland)》2022,27(24)
Leaves, husk, kernels, and bark methanolic extracts of Juglans regia L. were tested for their in vitro antidiabetic, anti-inflammatory, and antioxidant activities. For these purposes, α-amylase and α-glucosidase were used as the main enzymes to evaluate antidiabetic activities. Moreover, lipoxidase and tyrosinase activities were tested to estimate anti-inflammatory properties. Antioxidant properties of Juglans regia L., extracts were determined using three different assays. Leaves extract has an important radical scavenging activity and a-amylase inhibition. Similarly, husk extracts showed high total phenolic content (306.36 ± 4.74 mg gallic acid equivalent/g dry extract) with an important α-amylase inhibition (IC50 = 75.42 ± 0.99 µg/mL). Kernels exhibit significant tyrosinase (IC50 = 51.38 ± 0.81 µg/mL) correlated with antioxidant activities (p < 0.05). Husk and bark extracts also showed strong anti-lipoxidase activities with IC50 equal to 29.48 ± 0.28 and 28.58 ± 0.35 µg/mL, respectively. HPLC-DAD-ESI-MS/MS analysis highlights the phenolic profile of methanolic extracts of Juglans regia L. plant parts. The identified polyphenols were known for their antioxidant, antidiabetic (dicaffeoyl-quinic acid glycoside in kernels), and anti-inflammatory (3,4-dihydroxybenzoic acid in leaves) activities. Further investigations are needed to determine molecular mechanisms involved in these effects as well as to study the properties of the main identified compounds. 相似文献
629.
Molecular Diversity - Possible application of incorporating a well-known drug (benzocaine) with cyanoacetamide function to get a powerful synthon ethyl 4-cyanoacetamido benzoate. This synthetic... 相似文献
630.
Ullah H. Khan F. Taha M. Rahim F. Sarfraz M. Aziz A. Ullah S. Khan M. U. Ullah M. 《Russian Journal of Organic Chemistry》2021,57(12):1993-2001
Russian Journal of Organic Chemistry - A series of sixteen oxadiazole derivatives containing a thiazole ring were synthesized, characterized by different spectroscopic techniques (1H and 13C NMR,... 相似文献